The need for location information to enable pervasive computing applications in indoor environments, coupled with the unavailability of GPS in such environments, has motivated a large body of research on indoor localization. In particular, there has been a focus on leveraging existing infrastructure, such as, for example, access points in a wireless local area networks, to enable indoor localization. The advantage of this approach is that the cost of deploying a specialized infrastructure for localization is avoided. While the near-ubiquity of wireless Local Area Networks (WLAN), also commonly named WiFi-networks, makes WLAN-based indoor localization attractive, there is a need for a significant degree of pre-deployment efforts such as, for example, building detailed Radio Frequency (RF) maps or RF propagation models based on surveys of the environment, with these approaches.